The specific aims of the proposed Phase II program are to design, fabricate, and test in the prostates of dogs an improved instrument for hyperthermia treatments of localized prostate cancer. The instrument will use two cooperating transrectal and transurethral microwave balloon catheters to safely and uniformly heat diseased prostates to optimum therapeutic temperatures. Treatment temperatures will be monitored by means of therrnocouples and a digital microwave radiometer. The proposed hyperthermia instrument will conform to all applicable clinical safety standards and will be ready for clinical trials in a follow-on program. The instrument will be self-contained. Prostate temperatures will be optimized by a microprocessor that automatically determines the appropriate amount of microwave power to be broadcast by each microwave balloon catheter. The addition of hyperthermia produced by microwave balloon catheters to radiation therapy [external beam or implant therapy1 can be expected to result in improved local control and overall survival rates in patients with localized prostate cancer. Dual microwave balloon hyperthermia would improve the quality of life of those patients that have constricted urethras by producing biological stents in their urethras, and should also prove useful as a stand-alone therapy for palliative treatments of patient with local recurrences after radiation therapy. PROPOSED COMMERCIAL APPLICATION: Prostatic cancer affects many men and the overall treatment costs are extremely high. The proposed approach has the potential for providing and adjuvant treatment that may be performed on an "out-patient" basis to improve the survival rates in patients being treated with external beam or implant therapy radiation. The new type of catheters developed during the proposed program and the associated hyperthermia equipment will be important commercial products.